


Crooked Glasses, Crooked Smile

by singularweed



Category: Undertale (Video Game)
Genre: Bondage, Grinding, Heavy Dubcon, M/M, Multi, Possessive Behavior, and underfell is just horny as fuck, hhhh, selfcest, tell me if i forgot to tag something, there it is, this is really gay guys, this is really really gay, underswap and scientist are really possessive, underswap gets a lil yandere too
Language: English
Status: Completed
Published: 2016-01-25
Updated: 2016-01-25
Packaged: 2018-05-16 03:25:05
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 918
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5811856
Author URL: https://archiveofourown.org/users/singularweed/pseuds/singularweed
Summary: <blockquote class="userstuff">
              <p>Underswap finds out Underfell has been fooling around with a certain scientist. He decides to dish out the appropriate punishments.</p>
            </blockquote>





	Crooked Glasses, Crooked Smile

**Author's Note:**

> warning: this is really gay. self-indulgent, really gay sanscest. enjoy.

“Wh- what the fuck are you doing?”

Underswap smiled sweetly, digging his elbow further against the scientist’s neck. He gasped a little, heat rising to his cheeks.

“Tsk, tsk. Language, Sans,” Underswap clicked his tongue, leaning close to the other Sans’ face. “You know, you really shouldn’t touch what’s  _ mine." _

A growl escaped Sans’ throat, but it was quickly stifled by Underswap shoving his arm even harder against the other Sans’ neck. It felt like his bones were about to snap.

“F-fuck off!” the scientist snarled. “He’s  _ mine _ , not yours. So get away from me now and-- hrrk!”

A palm splayed out flat against Sans’ ribcage and shoved him against the wall. “I don’t think you understand me, mweheheh. I don’t take kindly to people touching what’s not  _ theirs.  _ You’re going to understand that at the end of this.”

Sans heaved, desperately trying to kick away his assailant. The pressure on his bones only increased, and stars danced in his vision. 

Suddenly, he felt the cold kiss of metal around one of his wrists. He jerked violently.

“What the hell-!”  _ Slap!  _ “Gh!”

“My, my! You really are disobedient!  _ My _ Sans is so much more well-behaved than this!”

The scientist glared at him, but he was helpless. He tugged at his wrists to be released, but he was only met with a tinkling, soft giggle. “Though, I do enjoy how much you struggle. This is fun!”

Underswap leaned in and nestled his face in the side of the scientist’s neck. He inhaled, letting out a small chuckle. “Well, I must say you’re pretty cute yourself, scientist! Even though you  _ are  _ a filthy-mouthed barbarian.”

Sans shuddered, a chill going down his spine and heat going right to his core.  _ Dammit _ , why was he getting turned on by this?

A tongue flicked out and licked a stripe up the side of his neck. Sans gasped and let out a breathless moan. 

Underswap gazed up at him for a moment. “Well, well! You’re enjoying this, huh? Wowie! I can’t believe you’re a  _ freak _ , too!” He cupped his hand around Sans’ neck and drove him against the wall again. “A freak who likes to touch with what isn’t theirs. I think I’ll have to teach you a lesson. But first… I think I want to have a little playtime with you, you cute thing! Maybe I’ll even invite my Sans to  _ watch _ .”

The scientist weakly struggled, knowing his fate was already sealed. “Fuck…. you…. He’s still mine.”

“Is that so?” A hand reached down and began to palm at the front of the scientist’s pants. He spluttered. “Wonderful! You’re already so hard for me, scientist! Great work, keep it up!”

Sans bit down on his own tongue, trying to stop his magic from reacting. He wasn’t supposed to enjoy this,  _ he should be fighting back--  _ A finger slipped inside the belt of his pants, lightly touching the head of his cock.

“Wh --” Sans threw his head back, gasping at the shock of pleasure that took over him. His glasses went askew, crooked and barely staying on his face.

“St- hrrk- Stop this, you--!”

“What’s goin’ on here?”

Sans gasped, eyes widening in horror.  _ Underfell was here _ .

“Babe…? Gh--! Babe, is that  _ you?”  _ He took a step forward and recoiled back when he saw the sharp glare Underswap shot him.

“‘Babe?’ Did I hear you right?  _ I’m _ your babe, not- not him!” Underswap huffed. “You’re all so  _ difficult! _ I’ll need to teach you all a lesson on being  _ obedient! _ ” Underswap jerked his hand upwards and shackled Sans’ hands securely against the wall. He leaned down and picked up the spare chains lying on the floor. “Now, come here!”

Underfell’s mouth hung agape, a scarlet blush rising in his face. He stared at the Sans chained against the wall, speechless.

“Underfell! Come. Here.”

Underfell cowed, bowing his head. Underswap grinned. “Perfect! I have just the perfect collar for you today, too!” He clipped the collar around Underfell’s neck, securing it tightly. Shackles were placed around his wrists, as well, and Underswap yanked on them, ensuring their tightness. Underfell mewled, his tongue hanging out of his mouth. His eyes were drawn back to the scientist. A small smile tugged at the edges of the scientist’ mouth, despite his…  _ compromising  _ situation. He stared at Underfell directly in the eyes.

“ _ You’re mine _ ,” he mouthed.

Underfell choked, a surprised gasp escaping him. Underswap growled. “What was that? Why did you do that?” He glared at the Sans chained to the wall. “ _ You,”  _ he snarled.

Underfell watched with wide eyes.

Scientist Sans grinned. “Me.”

Underswap’s face contorted. “No, no, no! This is all  _ wrong!  _ He’s still  _ mine! _ ” Underswap turned to Underfell, straddling his lap. He ground sharply against him. A broken moan escaped Underfell.

“Y- _ yours _ … I’m-”

Underswap grinned triumphantly, panting slightly. “See? He’s mi--”

Underfell’s eyes unfocused, and he stared at the skeleton chained to the wall, a blue light straining against the front of his pants. Underfell canted his hips forward. “Mm- Oh, you’re so hot, babe…” he muttered. “I’m yours… I’m  _ yours _ …”

Underswap’s face lit up bright blue, and he whipped his head around to stare at the scientist. “What are you doing? You’re taking up all his attention! He’s  _ mine _ , you know!”

Sans lifted his head up. His glasses were still crooked on his face, but his grin was crooked, too.

“That doesn’t seem to be the case…. heheheh…” His face contorted into a cocky smile. “Even after all this, he knows  _ who he belongs to. _ ”

**Author's Note:**

> //coughs  
> so, selfcest, huh? eheheheh....  
> leave comments and kudos if you enjoyed and want more. thanks, and stay classy, ya sinners.


End file.
